Citation:

Ozkaynak, A H., L. Needham, R. Whyatt, AND J J. Quackenboss. STUDY DESIGN CONSIDERATIONS FOR THE EXPOSURE COMPONENT OF THE NATIONAL CHILDREN'S STUDY. Presented at 43rd Annual Meeting of the Society of Toxicology, Baltimore, MD, March 21-25, 2004.

Impact/Purpose:

The overall objective of the NERL NCS Pilot Project is to investigate optimal approaches for the exposure measurements needed to support the planned Interagency National Children's Study. The objective of this task is to increase the scientific effectiveness of epidemiologic designs while minimizing costs by addressing exposure misclassification.

Description:

An ideal strategy for the exposure monitoring component of the planned National Children's Study (NCS) is to measure indoor and outdoor concentrations and personal exposures of children to a variety of pollutants, including ambient particulate and gaseous pollutants, biologicals, endocrine disrupting chemicals, metals, pesticides, among others. However, due to the large sample size of the study ( about 100,000 children), it is not feasible to measure every possible exposure of every child in the study. Thus, an important technical and logistical challenge is to develop an appropriate study design with adequate statistical power that will permit detection of exposure-related health effects, based on exposure and biomonitoring measurements on a smaller subset of the target population. Since the study will follow a longitudinal design, a related challenge will be deciding: a) which exposure-related measurements need to be assessed repeatedly over time; b) the timing of such repeated exposure assessments, and c) the appropriate type of direct and/or indirect (e.g., survey based) monitoring methodology to be employed, given various resource and participant burden considerations. The Chemical Exposure Work Group of the NCS project is currently undertaking an evaluation of these issues by utilizing the expertise represented within the group, as well as, those of outside contractors, in evaluating the available information on exposure monitoring in the context of an epidemiological study design. This presentation will summarize the recent findings from this NCS sponsored work group activity regarding potential alternatives for exposure and biological sampling, and inference of subject-specific exposures in the context of an epidemiologic study design.

Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy.

Record Details: